The Fine Wool Centre of Australia

I mentioned earlier how the Yass District is regarded as the Fine Wool Centre of Australia and, in fact, produces great amounts of pasture grown super-fine woolclips.

A friend has a grazing property just outside of Yass so I thought I would include a few images of his property. His home sits high upon a hill with a north-easterly aspect towards the rising sun.

Many years ago he split his holdings and gave his son half the property. Looking down the long driveway which climbs the hill to his home you can see his son's property and home across the way.

All the way around you can see the rolling hills and the water catchment dams that give him good pastures and permanent water.

National Dinosaur and Reptile Museums

Our Autumnal seasonal rains have not appeared for over ten years and March in that period of time has been unseasonably dry and warm. Until this year, that is.

As I have mentioned elsewhere we have our two grandsons, 4 and 7, staying with us for two weeks while their other grandparents are touring Egypt and Jordan - City of Petra is on their agenda. The boys are 'city boys' and really got a shock to see fruit growing on trees, vegetables in a garden plot and cows producing milk. They are also experiencing a 'dietry change' and eating good, wholesome and healthy country produce and not the usual supermarket chemical 'Heat-&-and-ready-to-eat' meals. Add to that good clean country air instead of Sydney smog and they are really get a 'lifestyle change'.

They must have caused a weather shift cause this March has been the coolest and wettest we've had so far for a decade. One day alone we got 50mm (2 inches) of rain and its been generally, cool, overcast and damp.

Yesterday we needed a break from their indoor games, nintendos, ceaseless DVD's, etc so we took them over to Gold Creek in Canberra, firstly to the National Dinosaur Museum and then to the Gold Creek Reptile Park.

Here are a few images from both.

Aidan posing in front of a diorama of a model of a raptor dinosaur on the hunt.

Aidan pointing to a real wooly mammoth skull complete with tusks which is part of the 'Hands-on' aspect of the Dinosaur Museum,  Sabre tooth tigers hunting in the background.

A model of a crested pteradactyl

Aidan and James pose in front of a model of Stegosaurus, the actual skeleton of which was dug up by a French Archeologist at a site in Africa in 1837

A pair of live Mountain Pythons laze under a heat lamp in their glass enclosure.

A live Diamond back Python, frequently kept as domestic pets by many reptile enthusiasts because of its placid and non-venomnous nature - it feeds on small mammals like field and barn mice, rats , etc.

Of course, couldn't miss out on our most aggressive of snakes - the Brown Snake. The Brown Snake may be found all over Australia. It has extremely potent venom, and although the quantity of venom injected is usually small, this snake causes more snakebite deaths in Australia than any other.

Sudden and relatively early deaths have been recorded. Its venom causes severe coagulation disturbances, neurotoxicity, and occasionally nephrotoxicity (by a direct action of the venom), but not rhabdomyolysis. There is another type known as the Gwardir (also known as the Western Brown snake) and its cousin, the Dugite spotted brown snake shown below which is found in Western Australia. A brown snake antivenom does exist but it is very expensive and deteriortes quickly so that not all hospitals can carry it and those that do usually only stock one single dose of the antivenom.

Geology and structure of the Maryamma District

This article is published to show the geological sub-structure of the Maryamma District in which the Wyangala dam is located.

"The Geology and Structure of the Maryamma District

South of Wyangala Dam, NSW

Lloyd White 2005

University of New South Wales

The Maryamma district is located approximately 40km southeast of Cowra, NSW. The field area is situated on the western side of the Hill End Trough, in the Eastern Lachlan Fold Belt. The field area consists of the Ordovician Adaminaby Group and Kenyu Formation, which have been intruded by the I-type Streamville Granodiorite and S-type Wyangala, Reids Flat and Wywurri granites of the Wyangala Batholith.
The lithologies of the study area have been regionally metamorphosed to greenschist biotite facies. The Wyangala Granite shows north-south layering, and the roof of the pluton is exposed along its eastern, to northeastern boundary.
The study area is located in the most deformed part of the Wyangala Batholith and characterised by the presence of numerous shear zones and folded granite. Shear zones occur in the Wyangala and Reids Flat granites, but are more prevalent in the Wyangala Granite. The shear zones found in the study area are along strike from structures immediately north of the field area, and are classified as part of the Wyangala Fault System. Lower-strain shear zones occur in the western side of the Wyangala Granite in the field area. Two-to-three high-strain shear zones have been identified and characterised along the eastern margin of the Wyangala Granite. Shear zones were delineated based on grain-size reduction, the presence of S-C fabrics and mylonite to ultramylonite development. Microstructural analyses of the granites, and the acute angle between S and C fabrics indicate that strain intensity increased from west to east in the Wyangala Granite. Strain intensity is also thought to decrease progressively south, as shear zones appear to merge into the dominant high-strain


Wyangala Dam Shear Zone.
The Maryamma district displays a complex structural history, consisting of at least four deformation events. The earliest deformation occurred in the Benambran orogenic event, and led to the formation of a pervasive, axial planar cleavage and tight isoclinal north-south trending and doubly plunging folds in the Adaminaby Group.
Granite emplacement occurred in the latest Early Silurian and is possibly associated with the oblique opening of the Hill End Trough. The Wywurri Granite intruded the Reids Flat Granite as a nested pluton in the same period, suggesting the crystallisation of the Reids Flat Granite was relatively quick. Continued east-west shortening in the subsequent Bowning-Bindian events led to the development of S-C foliations in the Wyangala and Reids Flat Granites, and weak S foliations in the Wywurri Granite. The differences in foliation development in the respective granites may be explained by mineralogical differences, or longer crystallisation histories in the more deformed granites. The development of both brittle to ductile structures in the Wyangala Fault System probably began in the Bindian orogeny, and continued with reactivation in the Tabberabberan. The slip direction obtained from S-C fabrics indicate that the Wyangala Batholith was possibly rotated dextrally in association with sinistral, strikeslip movement on the Wyangala Fault System. East-west oriented brittle-ductile mylonites with an apparent sinistral sense of movement occurred after the development of the dominant north-south oriented mylonites associated with the


Wyangala Fault System.
The Wyangala Granite was folded after the development of mylonite zones. Folding occurred in response to a long history of faulting and reactivation along the Wyangala Mount Darling Fault. Fault propagation originally began within the granites at depth.
A blind reverse, east-over-west backthrust developed adjacent to the Wyangala/Mount Darling Fault leading to the propagation of trishear zones from the deep seated fault tips. The combination of fracturing associated with faulting and trishear led to the development of tight isoclinal folds in the Wyangala Granite. The folding of S and C fabrics indicates folding occurred late in the region’s geological history and is probably associated with faulting in the Tabberabberan and Kanimblan orogenic events."

What this indicates is hard rocky valleys with shear sides surrounding basins through which waterways of the Abercrombie and Lachlan Rivers made their way down stream into the Murrumbidgee and Murray/Darling System.

Exploring this country is not easy with many precipitous climbs, however, the resulting views are worth the effort.

Many of these ridge lines are heavilly timbered and subject to lightning strikes and subsequent bushfires.

But the views are worth the climb!

Wyangala Dam

Although designed and built to the highest standards at the time, the original dam had shortcomings by today's standards. There were fears it could be subjected to unacceptably high stress by floods greater than those the spillway was designed for.

Investigations showed that raising the crest level of the dam by 23.5 meters would increase the storage capacity by almost four times. This worked out to be cheaper than building alternative storage on a Lachlan River tributary, as the enlargement work was carried out at the same time as strengthening the original structure. Work began after a Parliamentary Act was passed in 1961.

In 1971, the work was completed. The new embankment, built immediately downstream of the original wall, was made of rock fill with an earth-filled core.

A new spillway capable of withstanding a very severe flood was constructed, and a road bridge was built over the spillway. Outlet works were included in the design, with one low level and one high level outlet.

I have examined many of the remains of the old construction sites - where the granite rock was quarried and how it was moved, the concrete mountings that are all that remains of the cranes and steam powered engines and I will show more of these later on, as well as some historic images of the construction period.  There is even an old cemetrty located some kilometres away that I am yet to investigate, however, its remoteness is said to relate to the workers superstitions of having the dead too much in view.

The design provided for a power station to be built downstream if it was required in the future.

DIMENSIONS
Storage capacity: 1 218 000 mega litres
Surface area: 5 300 hectares
Catchment area: 829 000 hectares
Annual regulated flow: 490 000 mega litres
Crest length (excluding spillway): 1 372 meters
Maximum dam wall height: 82.3 meters
Maximum width at base (including old dam wall): 304 meters

(Extracted from "More Than a Dam - Wyangala" - originally presented by The Department of Water Resources.)

This view was taken from the northwest, and shows the rear of the dam wall in the middle distance, with the coffer dam (normally completely submerged) immediately to the right. The picture dates to July 2003, and shows the effects of sustained drought on Lake Wyangala, which stops several kilometres short of the main spillway.
 

Some views of Wyangala

The headwaters of the Lachlan River were discovered by Deputy Surveyor George William Evans in 1815, and named in honour of Governor Lachlan Macquarie. By 1817 Lieutenant John Oxley had explored the Lachlan from its junction with the Belubula River to the Great Cumbung Swamp. Settlement of the Lachlan Valley began soon after it was found. The discovery of gold in the region in the 1860's attracted many gold seekers, eager to make their fortunes, who eventually settled in the valley.

By early 1900, development in the region was considerable, although it was restricted by variable and uncertain river flows. A dam was needed to regulate the river flow and in 1928, following the completion of Burrinjuck Dam on the Murrumbidgee River, work started on the original Wyangala Dam

This is an historic image of the Dam at Wyangala - one when it was full and water flowed over the spillway and down the Lachlan River.  These days the dam is but a shadow of its old self - drought has taken its toll.

 
As this image taken earlier this year shows, the dam capacity is down dramatically and is currently around 7% of its capacity.
 

This does not stop some intrepid 'boatees' from fishing and skiing on it, however, skiing (for my money) is a risky business as there are lots of snags projecting above (and just under) the water surface and there are still some deep drop-offs.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

As the water level drops access to the water becomes more arduous.

 

The Park surface extended the boat ramps to assist the boating fraternity:

But after a few furtheer extensions those ramps became like roadways, so they gave up:

 

But the reduced water capacity has its compensations - its not so crowded a venue now and the flora and fauna off the area roam more freely with less people and we also found it a 'cool place' to camp. At first we towed our little Jayco van up their and used it for a base to explore the area with is rich in early Australian European settlement and industry.

 

We now have a more permanent base and will tell you more about that in futureposts and and our explorations of the region.

Ginninderra Creek and the Falls

Periodically, especially with end of Summer and early Autumn rains, the Ginninderra Creek would rise to overflow and rush towards the Ginniderra Falls - a spectacular water drop - which then flowed on into the Murrumbidgee River.

These waterways, with their large waterflows, provided an abundance of local freshwater tortoises, fish, mammals and waterfowl.

The Creek, Falls and Gorge area are now under the protection of the ACT Parks Service,

I've included a short video of the Falls trekking area:

http://www.youtube.com/watch?v=8OCI0_Ge6A0

Settlement and Early Construction

Yass lies on the junction of the Hume and Barton Highways and serves as an important interchange, connecting Sydney, Melbourne and the Australian Capital Territory. The first survey of the town was conducted in 1836 and the township was officially gazetted in 1837.


The Court House and jail were built in 1837/1838 and St Augustine's Catholic church was completed in 1843 and St Clement's Anglican church was completed in 1850. By 1846, Yass had 55 houses and 274 inhabitants, mostly clustered around Dutton and Warrambalulah Streets with a small settlement isolated in North Yass.

The Yass Gaol was later demolished when the larger gaol was built at Goulburn, some 84 kilometres to the north.

A feature of Yass are the hourly chimes from the post office clock tower, the wedding and church service tolling of the bells from St Clements Anglican Church and the automated chimes from St Augustine's Catholic Church tower.